Bracket from here: http://www.evok3d.com.au/Fire_Extinguisher_Mounting_Bracket_Skyline_GTT_GT_p/bra002.htm
Then an extinguisher from Big W/wherever.
Look into Marulan as well for some "track time". You sound like the type that wants to improve your driving (like most of us on here) so any track time will help. I speak from experience, my first two track days were in my crappy R31! No prior experience, and the skills I gained literally saved me a few times. Things like the way I held the steering wheel and hand movements changed after the first track day.
Enjoy, welcome and don't be shy to sign up for the membership, it's pretty cheap.